Obstructive sleep apnea in gestational diabetes: A pilot study of the role of the hypothalamic-pituitary-adrenal axis

Study Objectives: Obstructive sleep apnea (OSA) in pregnancy is associated with gestational diabetes mellitus (GDM). This propensity toward heightened insulin resistance in OSA patients has not been well characterized and may be related to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to (1) assess the prevalence of OSA in pregnant women with GDM, (2) evaluate whether HPA axis dysregulation relates to OSA, and (3) investigate the relation between insulin resistance and OSA. We hypothesized that OSA is prevalent among pregnant women with GDM and that women with OSA will have higher levels of insulin resistance and dysregulation of the HPA axis. Methods: Twenty-five pregnant women in whom GDM was diagnosed were enrolled. Subjects answered sleep questionnaires and underwent in-home sleep studies using a level III device. The presence of OSA was defined by apnea-hypopnea index ≥ 5 events/h. Homeostasis Model Assessment of insulin resistance was derived from measurements of fasting glucose and C-peptide levels. Three salivary cortisol levels were obtained across 1 day to assess circadian variation. Multivariable linear regression analyses were used to assess associations between variables. Results: The sample consisted of 54% Caucasian pregnant women with a median body mass index of 36.1 and interquartile ratio of 10.6 kg/m ² . OSA was diagnosed in 17% of participants. Circadian variation of cortisol was preserved in women with OSA. Women with OSA displayed blunted cortisol awakening responses. Conclusions: OSA is prevalent in women with GDM. OSA is associated with preserved circadian variation and blunted cortisol awakening responses.